This invention relates generally to and methods of fabricating dynamoelectric machine stator assemblies and and more specifically to methods for making, insulating and mounting of winding interconnections within a stator assembly.
As is well known in the prior art, dynamoelectric machine stator assemblies often comprise a magnetic core having a bore, axially extending slots, and windings each comprising a plurality of coils formed by multiple turns of a conductor. The multiple winding turns have side turn portions which are disposed within the axial extending slots and end turn portions which project from the slots and which are disposed about faces of the core. The windings are electrically connected to each other and external power conductor leads in various configurations depending on, for example, whether the windings are to be connected in parallel or in series, the number of windings, etc. with the interconnections being made by techniques such as brazing, soldering or crimping. Connection points resulting from the electrical interconnections are electrically insulated and generally disposed within or about the end turns of the windings.
In making interconnections within a stator assembly, the ultimate goal, of course, is to make interconnections which are reliable, that is, connections which are held secure, properly insulated and which will not be subject to damage during subsequent assembly operations or during motor operation. In addition, it is often of extreme importance for many applications that connections must be made and insulated within the space requirements imposed pursuant to stator assembly mounting restrictions. It is known that interconnection points can be insulated by pulling or threading each conductor through an insulating sleeve until the connection point is disposed within the sleeve, for example, as diclosed in Reynolds U.S. Pat. No. 3,912,957, which issued Oct. 14, 1975 and which is assigned to the assignee of the present application. Sleeve type insulators are often secured by tucking or embedding the insulation within winding end turns. Problems are often created by such techniques of securing the insulators and connections due to the fact that burrs or sharp edges often exist at a connection point; thus, pushing or forcing insulators within the end turns can cause these burrs to cut through the insulator and into the insulation on the winding conductors causing a short circuit and motor failure. The likelihood of such a problem is especially acute in situations where a stator assembly is subjected to an operation wherein the winding end turns are shaped and compressed after the insulator or insulators have been embedded within the winding end turns. With connection insulators embedded within the winding end turns, more pressure must be exerted on the end turns in order to compress the end turns into a configuration conforming to mounting requirements; thus, the likelihood of damaging the connections is increased during the pressing operation.
Of course, it is known that such problems as cutting of insulation can be alleviated or eliminated by removing connection points from the winding end turns and mounting the connection points within insulators attached to the stator assembly core.
However, known prior art approaches for performing and insulating electrical interconnections within a stator assembly and which involve insulator mounting out of the winding turns often require modification of existing stator assembly components such as additional mounting holes in the core or changes in slot insulation. In addition, some prior art approaches involving insulator mounting outside the winding end turns require insulators which cannot be used in circumstances where mounting space is at a premium. Further, known prior art approaches require that connections within an insulator be performed individually, that is, one at a time; thus, extending stator assembly time. Still further, prior art connection methods often require multiple insulating sections disposed around the face of the core or else, connections to a single insulator involve draping of wires about the end turns which is undesirable in many motor applications.
Accordingly, one of the objects of this invention is to provide new and improved methods for fabricating dynamoelectric machine stator assemblies which overcome the above-mentioned and other problems and deficiencies.
Another object of the present invention is to develop new and improved fabricating methods to reduce or eliminate motor failures resulting from winding interconnections.
Still another object of the present invention is to provide new and improved fabricating methods to provide winding interconnections that are readily accessible and securely mounted while minimizing connection insulator mounting space requirements.
Yet another object of the present invention is to provide new and improved methods of establishing and insulating electrical interconnections within a stator assembly while reducing end turn pressure forming requirements.